Water-heater.



F. L. 0. 'wADswoRm WATER HEATER. f APPLICATION r|LEDjMAY25.19'12,

Patentedv Mar. 14, 1916.

(lllllf.

F. L. '0. wAnswoRIH.

` WATER HEATER. APPLIcArloN HLEDMAIY'ZS. 1912.

Patented M111. 14, 1916.

wnj'NEssss F. L10. WADSWORTH;

WATER'HEATER. APPLICATION FILED MAY 25| ISI'Z.

' Patented Mar. 14, 1916.

3 SHEETS-SHEET 3.

lNvENTo'R `H317. wfg/ffii.;

t e "art of Water heater construction. Other objectslof my invention will appear more FRNKVL. 0. WADSWORTH, OF SEWICKLEY, .PENN'SYLVAIWIA v i Specification of'Lettcr's Patenti yWerimetinznrsa.

'Application mea may 25, 1312. 'serial No. 699,816;

To all/whom z'tmcy concern.' f t' `Be it known thatl I, FRANK L. O. Wansw'oRTH, fa citizen of the United. States, residing'at Se'wickley, county .of Allegheny, and State and useful 'Improvements in l specification.

My' inventionA relates to .control mech- .lof

anism for hot'l Water .heaters ou either the {soralled` instantaneous or the storage tank E-,type Some of the objects `of my invention ,"are-first, It0' @trol mechanism Which will hold the gas'` l valve thatregulates the supply 'of fuel to "themain burners of the heater eitherfinthe provide a .thermostatic confull open or the-.completely closed position,

n so as to avoid the gradualturning onor shutting ofi"l of the fuel supply when lthe temperature 4of theA Water in-the heaterv is near the `point vlde a mechanism in which the first named the gas valve parts objectl is accomplished not' lby any vdirect action of the 4vthermostatic elements' on the am gas-valve, but by theiindirect control o flpressure means which ldo act directly on Y and thereby eHect the movement of thoseparts both with rapidity and with great positiveness; third, to `.pro-l Vvide a construction of eXtreme -simpllcity that can be' manufactured -at'small cost and' i 'one `which will not be liable 'to `get out of order runder` the lmost severe rand tryingservice; fourth, to provide .improvements whereby in instantaneousheaters, the main gas valvevull be held closed, no matter what* mayy beV the l position of the thermo- 'c static control parts,-When no `Wateris flowing through the heater; andflifthto provide a formi of contrcl mechanism which, as

aboveV indicated,fmayf be; if desired, used @interchangeably yon either typezof heater,

subject only to' such mechanical modification as A'may be made by anyone skilled 1n --fully .after the various structures, which- I have illustrated as differentk embodiments of my inventionhave been described'. Y l In. the drawings Whichform aj part of this specification,Fig;` yl illustrates in side `elevation the general c onstru'lctmn'ly and arrangement partsfof a 'sto Lgey tanlfheaterof' Pennsylvania, `vhave .invented f certain new p Water-Heaters, Iof* which the following is 'a Y at which the therm'o'static lmechanism is'desired to act second to pro` Figs. 4l0 and ment of parts illustrated l of the heater; K are the gasburners (are located beneaththeA coils of the heater and may be of any preferred type; L is the .100 governing the supply of gas to the burners IC; M isa casing which contains the conto Which'one o f my improved control mech-r anlslms 1s applied; Fig. 2 1s an enlarged ver# 1 tica cross-section through the center of the control mechanism shown in Fig. 1;

' Patented Mar..4 14', t19,16. p

Fig. 3 is a rear elevation of one of the parts show vn 1n Fig. 2; Fig. l 1s an enlarged crosssectional View through a second form of control mechanism'which lalso 'embodies my improvements, and may be used 1n place of the' mechanism shown in Figs. l, 2 and 3; Fig. 5'is a detail view of a part of 'the construction illustrated in Figfl; Fig. 6 is a view, similar to those of Figs. '2 and 4,

one of my improvedcontrol 'mechanisms lparticularly designed for `use 4With a heater vof -the. -"so-ca'lled instantaneous type, this mechanlsm including means for holdingy the main gas valve closed'when no lvvateris 4flowing through the heating receptacle;v Fig. 8 illustrates a modification of part of the construction shown in, Fig. 47; Fig. 9l illustrates another embodiment of my invention as applied to thev control mechanism of an instantaneous coil heater; and 11 are detail views (fullsize) of a thermostat construction Which'may be used in conjunction with the mechanisms of thepreceding figures. j

Referring first to they general arrangein Fig. 1, A is a` storage tank or reservoir having av cold Water 'inlet pipe B leading from the main and a hot Water outlet pipe C leading to.

the houseiixtures; D is the. casing ofthe heater, which heater 'may be of at their upper -ends into a header F and at their, over ends into aheader-G; H is the gasinlet pipe; I is' the gas pipe-'leading from the control mechanism to the bulrlnethermostatic controlling mechanism lfor trollingl mechanism for governing the operation of the gas valve which is Ialso c ontained in the casing; N is the hotlwater r1ser` leading ,from the header F to the reservoir A; ands@ isthe return pipe 4leading from the reservoir to the lower header G.

p any ap-v proved type; E are the heater coils leading showing other embodiments ofmy invenf. tron; Big; 7 -1s a vertical cross-section of which communicates `with the right hand :10.

'plate 3 riveted to said lwall.l Gas is let into this' casing through the supply pipe H end' of the casing chamber, andthe main gas 'valve tzwhiclicontrols thepassage offuel tothe gas outlet pipe I is vmounte'd -on a thinleather diaphragm 5 which" is clamped' in. positionegainst the front head-of the cas-' x ing M'.by"means .offa shell recessed cap 6:' The space between'the diaphragm 5 and cap 6 is provided with two port openings? andi .8 which may be closed respectively bythe puppet valves 9and' 10 that are heldagainst@l the leather' faced seats `11"and 12 by means of springs 13 and 14.4 The first valve 9 is on the wall'of the gas v alve casing M and is threadedatthe right hand end to receive an adjustable thumb nut1 16 access -to which can` be obtained by removing the ca 17 The lowervalvelO is placed in'- a tu ular v" .-thumb nut being also 'accessible bythe re.

recess 18v which is closed atthe right-hand end-by a 'st uling box cap'19 through which lthe 'stem .20 vof 'the-.valve passes, and the outer end' of' this stemis threaded to receive moval of' a cap 22.. The cel'itrall lspu'd'2 of the'. gas v valve casing is perforated and threaded to 'receive and support-the .thermostat member which projects horizontally .into the water in the tank A. Thifsjtherl'oj mostat is; ofthel usual'composite construc-r .'"tion comprisingan outerexpansible tubular l 'element 23 of brass, copper, or other metal having a' high coeiicient of vexpansion and an inner vnegative' element 24 of 1ron,'1nvar l metal,'porcelain, .carbon .Orother material' 'having avery low 'coeiicient of' expansion,

the inner 'end of the negative element being y abutted against orrsecured -to and closing Y the inner endl of the outer element, and the outer end of saidnegative element terminating in a -pivot -point which ,engages "with va coned recess in an adjustable plug 25 -at the center of the thermostat lever 26.

.This vthermostat lever is provided witha V-shaped slot 27 (see Fig. 3) which is filed '."or machined across the back of thev leverv prior, to the insertion of the plug A25, and 'serves-'to ieeive .the pivot points of the `supporting screws 28 on which the lever 1s mounted, these screws being located symv metrically 'on each side o if5the' central plug .25, one behind and the other in front of the site ends ofthe thermostat lever 26 are vconi-V `cally perforated to allow the passagel ofthe at its 'center'. tofrr Liricas lvalve. stems .ihsland 'I 20, and compression spring =.-:29' is provided to` keep.

in operativeengagement wi" pivot point'- of .the negetiyelthermostat ellement 24.-. The main gas valve/4 is threaded 30, the endv of 'which is connected" to 'a Weala tank A is at or above vthe .point at which itv is vto bemaintained the thermostat isI .ex-

panded sufficientlyto allow the spring 29 'Ito bring the upper arm of the thermostat lever 26l into engagement with the thumb "hut 16 and thereby lift the1 valve -9 from 'fits seat-admitting gas to the shallow 4cham- 1 providedl with stein 15 which passes 'loosely through a lug projecting inwardly ber between the diaphragm 5 and the cap 46.. The pressure of this gas on the back ot the diaphragm 5, supplemented by the 'slight pullfof tlie tensioni spring 31, keeps the gas the lever 26' vthe terminal- -L c an adjii'stable 'screw .tension spring 31that normally holds they" gas valve lightly against its seat. By turn# 'ing the screw 30 `the tensionl of the s ringi As the temperature ofthe Awater inthe'tank falls the thermostat member contracts and moves theupper end ofthelever 2G tothe. lefty thus vallowingthe valve 9 to seat-l itself Vunder the pressure of the spring 13. As the.

movement continues the :lower end of the thermostat. lever will be brought into engagement. Withthe thumb nut 21' therebyv lifting the valve 10 from its seat andallow-fv .ing the gas back of the diaphragm 5' flow out through the port Sinto the tubulaichambercontaining'tlie valve 10. From this .tubular chamber the gas' escapes either through the port 33 which'leads from said `chamberjintotlie pipeI o-'r-through -a port- 34 lwhich leads from said vchamber to the exterlor of the apparatus. In either case the "escape or' the gas through one of these two ports relieves the pressure on the back of the. vdiaphragm 5. and the pressure o n the valve 4 will lift the latter from its seat and all-ow fuel to flow from the main supply pipe H tov the fuel .out-let pipe' I and` thenceon to the.

` main burners of the heater where it will be Vignited b v the fiame of the usual pilot light supplied for that' purpose. -The main gas A valve '4twill remain open v'until the tempera- 'ture Aof the water in the heater has been raised to such a point as to cause the thermostat control parts toonce more. assume the position shownin Fig. 2 in which .the ralve 1 0 is Aclosed andthevalve 9 is open. It will -be observed that the opening vand closing 'movements ofthis valve' are produced re-A spectiv'ely by the unbalancing and balancing ofthe gas pressures on the 'two sides of the diaphragmhiember- 5 which carries the 1 ni'vmoaa i Valve, and v'that in consequence of this, these movements are performed With great rapidity immediately after-@the respective openings of the two 'valves v10 and 9. `With an ordinary' gas pressure of about one and one-y quarter; ounce to the square inch the diameter of diaphragm necessary'to support and operate the valve 4 with the required rapidity need not be over four inches; .andthe .space between this diaphragm. and the cap 6 necessarv to allow the requisite opening of said main valve need not be over one-eighth or 'three-sixteenths of an mch.

"than two cubic inches, and this volume of ated at v'ery frequent intervals. Even if 1t terio'us effects.

gas can be discharged directly into the room in which the heater isv placed Without dele.

The control mechanism of storage tank heaters is not, as a rule, operoperates' asm'any as one hundred times ak ,day that is fifty opening and fifty vclosing movements (which is many more times'than it usually does operate) thetotal volumefof` gas discharged into theroom in twehty-four hours would aggregate only about one1twentieth of a cubic oot,a quantity altogether too small to be noticed in .any Way. But it is'. Vnot necessary in the operation of this device that the port 34 should be opened tothe eX- terior of. the apparatus.- It can be closed by a cap (shown in dotted lines) .thereby compolling all of the gas which flows through the port 8 'to `pass out through the port 33.

` It willbe noted thatat the time the port 8 is openedthere is no gas in thepipel with vhi'ch the port 33 communicates and gas therefore. Will escape into this pipe through a port 33 as readily as vit Will through the port 34.1 VVhenj the valve 4 1 is openedfby the Withdrawal' 4of .the gas from the back' of-` -the diaphragm" 5 and the fuel Hows through 'into the Ipipe I it isprevented from backing .up 'into the port 33 4and restablishing a pressure on thefback of theldiaphragm 5,

both by. the form ofv -the port opening33- Whichlisso located'as to act like a reversed ejector oriiceeeand'` also by a thin'exible Hap" valve 35 of leather, chamois skin or Similar suitable material.

ist

'. In the' construction shown-in Fig.` 4- the arrangement'of parts is in many respects thesameas" 1n the construction of F 1g .j,2',

.infact the two `forms of mechanism are practically interchangeable, and differl from each otheronly in ldetails ofthe construc- 't'ion"ar'1d ,the arrangement ofindividual parts. In lFigtfl' as in Fig. 2 the casing M contains a main gasv valve 4 which is,se curedlto the center of athm flexible leather" diaphragm 5, "onvthe `right hand side of z this diaphragm, .c., 'on the `sideopposite fthe gas. valve-4', is ashallow chamber,` cor- 'respondingto the chamber on the lett hand 9 which is normally held Hence the totall volume of the chamber 'between the diaphragm 5 and the cap 6 need .not be `more ,that

l valve chamber 37 and Ya. port 38 1that leadsl intothe'space back of the .diaphragm 5.-

tral boss of the valve 9', passes through a stuffing box in the cap 39 and terminatesfop? posite the head of an adjustable screw 16. that `1s 'threaded into the upper end of the thermostat lever 26. i vided with a leather part of the chamber thlrough 37, I A valve." against its seat.

The stem 15 engages with the recessed o en- The stem 15 is pro# faced .collar 40, and.'

a spring- 41 interposed between thiS'collar-Q and the valve 9serv esto 'seal 'the opening around the valve stem-When the valvefis.l closed-even though, the .stulngbox may be.qu ite loose. gas valve casing Mis provided With a SGC- ,ond valve 10 of exactly the samecon'struction and mounted 'and operated in exactly the same 'Way' as the upper valve 9. The valve chamber 42 is provided with two port openings one of which? 33. opens into. the

The lovver portion of. the I gas outlet'pipe I., and the other-of which 8 leads into the pipe 43`which communi. cates With the port 44 formed in a perforated division tube a (see detail of F ig. 5).` The s'tem Q Oof the lower valve 10 terminates' opposite the head of an adjustable-screw 21 threaded into the lowerv struction as that `shown in Figs; '2 and 3` and is actuated byV afthermostat member.

Which is alsofof the same construction as previously described.' The gas valve plug 115 in thefpiloit light i end of the lever l f` 26. This lever 1s of the same general con-` l is provided'a't itscenter with an adjustl able screw 30 which bears against a light compresslon lsprang 31l that 'aids in holding thefgasv valve aga1nst 1ts'seat\vhen the arts 9' and 10 are in position shown in Fig. 4.'

-The operation of this mechanism is the same as that 'of the construction, -previously described and -Willtherefore be readily understood without an extended description.

The 'position of parts lshown in the ligure i' is that assumed when vthe z temperature of vthe Water in the tank' is at o r above the point at which the control mechanism is ,setto cut off'the'gas to the main burners .of the heater.l In' this position. the thermostat member has expanded sufficiently .to

the screw y16 into engagement with the st'emlv of the valve 9 andi-aise the latten,` from its seat thus exposing the right hand side of the diaphragm member 5 to the pressure of the gas in the supply pipe H This Pressure ou the back of the diaphragm member 5, aided by the vow-same of. the

.allow the'spring Q9. to bring the head of i rspring 31 holds the gas valve 4 f'fseat and 'pipe-H to the pipe I.' When the ture of they water in the tank i the right thus allowing the valve 9 to seat differs somewhat from that shown in any of the preceding figures both 1n details of con-g l itself.. tinues, l0

stem 20,

As the'movement of this lever con- 21 is brought into engagement with the and thisin turn moves the gas valve 10 away from its seat' and allows the gas 'ba-t escape either through the port opening 33 or through the portI opening 44. Both of these port openings may be left opengat' the Sametime or either one may be closed ofi". If the port opening is left open andthe port opening 44 isclosede-as by closing -"the plug valve in the pipe 43-the action will be the same as in the case of the correspond ing use of the apparatus of Fig.k 2. I f the portl 33 the gas will be siphoned or sucked 'out through the las'tI named port by the ejeetor action of the stream of gas which is constantly flowing through. the pilot light tube a. This ejector action may be increased by making the perforations 46 in the block 45 smaller in area than the cross-section -of the pilot light-tube thereby reducing the.

pressure at the lower surface of the block '45. This reduction in pressure can be still further increased, if desired, by forming lthe lower end of chamber through which both air and gas will pass to thepilot light. This latter construction however is not necessary to secure the efiicient action of the apparatus, and has not 'therefore -been specifically illustrated. The removal of the gas from the right hand side of the diaphragm 5 `allows the gas valve 4 'to be opened by the unbalanced pressure of the gas on the right hand side of the diaphragm thus admitting a fuel supply to the gas outlet pipe I-and the main heating burners supplied thereby. As the water in the. tank is once more heated up the thermostat member will again expand allowing the spring 29 to move the thermostat leverQG until the head 21 A1s out of engagement with the stem 20 and the head 16 is in engagement with the stem 15. This movement of the thermos'tat levery first allows the valve 10 to close,

-and next presses the valve. .9 open, there- 'by restablishing the conditions first de scribed in which both sides of the dia-l phragm member 5 are exposed to equal gas 4 pressures, and the main gas valve 4 is held closed by the pressure of the spr1ng'31-.

The control apparatus shown. 1n Fig. 6

bythe continued contraction of the thermostat element, the head ofthe screw` of the diaphragm member 5, to

is closed and thea port 44 left open this block into a mixingI Istruction andof operation. The main frame 1 13 of the tank A.` This casing is provided as before with a gas inlet pipe H leading into the top of the casing, and a gas outlet pipe I leading from the bottom thereof to the main burners of the heater. As before the casing is provided withv a division wall which separates the inlet and outlet openings and this ,wise suitably secured to the end .or side Wall division wall has a central opening in which I the main gas valve 43 is located. Butthis gasvalve instead of being mounted and supported directly on a. diaphragm member as in the preceding construction, is secured to short stem 51 which projects through the mainr gas valve port and is provided at the 'other side thereof with two washers or heads between which the flexible leather diaphragm is clamped. A port opening 73 leads from the upper part of the gas valve casing-#with which the inlet gas pipe H is in communication-to j a vertical tubular chamber 373,',and asecond port 383 leads from the lower end of this chamber Yinto theV space hadn-'z'.` e.,.to the right hand of the diaphragm member 53. The,y port 383 is opened and closed by means lof a valve 93, this valve being slidably secured on. a stem 52 and held in position thereon by means of spring 54.. At the lower end of the chamber back ofthe diaphragm 53' there is a'second port opening 83 which is provided with twoA branches, one 343 leading to the exterior of the apparatus and one 833 leading-to the in-jl terior of the gas outletpipe I.. The port 8s is opened and closed member ll03 which is-also slidablysecured to the stem 52 by a threadedcollar 58 and a. shortcompression b v means ofv a'valve v v means of a tubular cap 55.

and a stem head 56,. The stem 52 e- Xtends upl 2 and serves to-keep rear head of the gas y'through thetubular chamber-SZsfafnd an-up. l

shown in the figure,

ber of this thermostatbears lagainst the short arm o-f the thermostat lever 263, and the long 'arm of 'saidllever is provided with" an adjustable screw 59, this screwbearing in turn against the short arm' ofasecond" thermostat'lever 60. The long :armof .the

.lever GOAengages with the upper end of the stem 452 and is'heldin engagement therewith 'by the tension of thespring 5 7. ,The operation of the mechanismofFig.' .6 f

just -described is,'asf alreadjv stated,"sortie-jy what different from that -of the. preceding mechanisms. In the case of r the :last de-y :scribed apparatus the parts alfeso' arranged u fiume@ 1 Tend edj.1 1sted 'that the'meii-ges valve lis elosed' when there is. no pressure on the'.

heeleorfrightjhand vside of. the diaphragm Whereas; ,gill of. vthe" preceding. mechajgfis 'velveis only' closedv when ,the Ading V'side' 'of :the valve supporting i ile. Fig. 6 .the relation of thejtherrhostt lele'- st'ancesthe space bac-k .of .the .diaphragm f emptied of 'gas vwhichipasses out eitherflthroughf the lport epeniri'gfi 34l;z-f preferably 1out through$-thefiliclined` port eperiig 1333, into thegas.' outlet. pipe leed of 'pressure 0n the' 'right :hehd' 'side'. fof the daphregr'rtleeves the 'gsfvalve exhos'ed'rto 25..

ments te the.- feohriectihg. lever I'heehfinisinl is Q1'. "Tem isl raisedby the spring 'until the ve lfve.93 has 'heericlosed'end' lthe Vvalve 10.3 hasheen. opened. Underfsueh cir-eumli e .is vv'exposed tei v the gas preseureflljshe main nle'tfpipe. ..Thus, las shown 43 sopen the beth sides of =thediaphrztgn member are exposedxto vthe'same gzis'pres sui-e, save that the static' `pressure of the ges. enl the right handfside is ehvefys. slightly Agreater than the kinetic ormv pressure of 'Je the gee on' thelefthand side,v The mein ges' .valve'will therefore remain open untilthe.

lexpansion of the thermostat memberwdue tothe rise in temperetur-'e of the VWeter'iii 4thetank-#41ers 'allowed the parte. to *ence-1., 75

more assume thepositien shown iirifflllg.y

in which the valves 93 and -heve heem;l

4.suecessivelv vclosed .and opehedfyflhe openingfof the letter .valveyas elreedvexplained relieves the iras pressure on .the back er'. right hand sideof thediephregi-i, either thefdischargelof Athe.gee.niptethe'. openi f ges valve casingzto the.meinybupnersfoi the elosiiige-the"operiingtothe discharge Fig. Zalillustretes e constructioh ofcohitrol 59 pertS-'theuppervtlve 9.3 remain-,ing Seated mehe'nsmlwhieh 1s particularly designed l -heet'er.^; llhegas valve under the. 1pressure o ,the temperature (if-fighi? the .lippe'ifid'lffihelthermstat lever 26?' "file the right,f and through fthe" aci ti0n1fof7the second*thermostetgflever 60 de-- sere on the/beek of. the .di :iphregi member.

lig f the 'meiiigas' .valve whenever the temectlgfap v'alve?-53.f..lnstead'iofthegas 85 f beingdischarged'fronrthe hack of the-dia,-

. '"phragm' inth-iS-menher itk may., of' course,

bef discharged f er; sucked mit inte` the pilot f .-lght'tuhe`iii the-seme marmer already lllustratedend-,deseribed in "cormecti'on with Fig; 9,0

pereture "leif-gtliei{Waterinthe tank' rises `Ajustifient of' theserew f5?) and v the adjustmeiitj ofthe collar-*'53 eli thestem' 52, lThis 'letter- .-'adjustmetmey be' conveniently etpress thegstem 52agairist thet'erisioefof the the coller lageirist rotatienby meansv of sprilg- {37,}The` dowvvard movementofthe le lug.enter.111gsJ slot onthe adje-cent Wall 'fof undetheltension of the spring :54, A. @Sight `further:.djoWIiivvalrd movement of thesteiz.;

fre 'e'vesv thelva'lve 9'? of the restreiningnaetion ofthe'sprmg. .545 l und the lattervalve' .will

then, op lizlfellowing gals tei pass. from the gas'jir'xle pe-Hthrogh the ports Zjfand vedephragm .member 53:

, miriedetelv opens? the gasv val-ve easing.

.fstantaneel type, in Vwhich theliquid passes '-through'a coil kof? copper pipesfwhiehyere exposed directlyfto theheet `ofthe mein burn-v ertsv 'meeneemt-.Lits `Well I known Character 'the s"1'i 1''3` turef 4vheckL thereiste theright' 'y wie.

li: he'. 19935723; Xissued 3Q,' .19112 impreved construction ,is reed-ily above or ffells-fbeljew predetermined points-'105 -Wh0h1m2ty be" veried efdesired bythe' edmined-hy rotating `the stein 52 find h'olding'l'lo only 'bep-'admitted to theA main burners while the water is flowing through lthe heating sure means, but also by the'po'sition vofa` water actuated velement4` placed in the path of the inflowing -water to the heater coils;

' c This wat'er'actuated'element is indicated in the figure by the reference numeral 62. 1t is located in. acylinder 68 which is provided at itsfront end with an inlet port in commu-A nication with the pipe 64 leading from-the cold water mainrand is provided'a-t its rear lso en d 'with a second port which is in. communi'- cation with-'thepipe 65 which leads to' the cold waterinlet 66 entering the top coill of which is loosely held in position in the front head ofthe, cylinderl 63 by means ofV a'iiut 68. A 'stem 69'is secured to'the left `hand end of. the central perforated'boss 62? of piston'member 62, passes loosely through@ the plug 67, and through a stuiling'zbox inthefront endl of the cyl'inderhead and en- I ters the wall ofthe gas valve chamber. This stem is''.'prov'i'dedv with a collar and' leather washer 70 which serves to lsealthe o pemhg .-'ar'oundrthe st in 69 and prevent the escapeof water-through the adjacent stuiiing'box.

=- ;-The plug 67 is provided' with tapered' ports 71 Whichare completely closed when the.;v ypiston njreinber62'is in the position` sh own 5 .f-invthe fgigre, but which gradually vopen as .'fsaid pistongis moved to theleftiand allow.'V l "j-Water to flow from the front end of the cyl- 'inder through the'central perforated, bess of the. piston to the rear end of the cylinder.

The stem 69 extends through the piston-62 and is provided at th'e extreme left hand end" with a spring check Valve washer 72 which is 4held lightly against the adjacent perfo-l rated face4 of the central boss lby a 'weak `spring 73.. A stili vspring 75 is interposed between the left `hand side "of the pistonv member'62 andthe rear cap of the cylinder 63,. and serves tof'hold ythefpiston member normally inthe position shown-in the figure 1 in which, .as already stated, theportl open-- ings leading from the inlet p1pe64 to the.

. pipe y are closed,s`o that. no liquid can'ow from ,the .water main into the heater coils. e The supply 'of "ga's' enters the main: gas valve- -casing M through an inletpipe H, and-'when the main gas valvev is open. passes outthrough the .pipev` I -which lleads to .the main burners; The main gas val-ve; 7 ,6, Iwhichicon@A4 trols the flow' of fuellismounted at the center of'a.thin flexible leather' diaphragm 77. A. port `opening 7 8 leads from the top portion .of the gas Valve chamber-.to al second chamber `79 'which contain'sthe thermostatgi-.

arriva-'092 cally ac tuatedfmechanism by'meansof which which hot water is led .to the lhouse supply system, or to. such other point vof use afs lmay the 'mam gasvalve'i's'opened and'closedac .in communication with the pipev 82 through be desired. -This thermostat is ofthe usual composite construction comprising anoutertube 83 of brass, havlnga high coefficient of expansion, and

.an inner: 'negative element 8l -Whichis made olf steel, Invar me'al, porcelain, carbon or .similar material hl ving 'a' very low coeffiv joient of expansion. The outer positive tu? the heating chamber. The piston@ is perl l Y i i forated at itsv center to receivea .plug 67v at `its upperend'and at that point is secured',

or abutsagainst the adjacent end of the in# nernegative member 8l.- The latte'r'terini. I natesl at its lower end ina knifejedge-which copper, zinc orother metal bears against, a'therinostat lever 85, the outer end lof. which is provided with an adjustable screw 86 engaging 'With-a .secondgthermostat lever 87.A The latter lever engages. in turn lwith' a stirrup or fork 88 lthe vlowerend of g whichis pressed upwardly against the thermostat lever system by means ofa strong compressionspring'89. TThe lower cross-bai; ofthe stirrup 88 is slotted"to receive vthe head of alvalve stem 90 carrying the doub le headed valve"91. The, 'upper head of this valve 91 serves/to'open'and. 'close the port 92 which leads| from the' chamber 79 which opens into the gas'o-utlet pipe ILWA spring 95 is interposed between the-head of to thejspace .back of the main` valve diaphragm 77. g The lower head of thevalve 91 a downwardly projecting stem secured to the valve 91 and the upperend ofthe vport ichamber 94. This spring'is of considerably less tension than the spring-'89, so that when the 'valve 9l is acted upon by the-'former sprilgjalone. it will be held in the'positiorr lshown inthe figure thereby closingthe port 93p; but when said valve is actedn'pon'by both springs it will be raised by thejsuperi'or tension of the spring S9 thereby closing thev port opening 92.

The operation ofthe control apparatus of Fig. 7 is as follows: lVhen thewater is. at rest vinthe heater coilsthe pressures on both sides ofthe water actuated member 62 will be the same, this member will beheld against thefront endy ofthe cylinderg by thel spring 75. In thisposition .ofiithe piston member the end of the'stem 69 which enters .the main gas valve chamber, bears against' the center of the main gas valve 76 'and holds the latter firmly closed againstits seat, and prevents its being opened by any action of' the `thermostatically `ccintrolled mechanism.

But as soon as Water `isyvithdra'vvn' from the heater coilsa's byopening a tap inthe-diej. charge pipe S32-#the press1` .1re in the heating f `c ha`n`1ber-and inftheffl'eft hand end oi` the f cylinder is reduced, andthe piston member 62 is' moved to the left' 'thus opening the ports 7 1 and4 allowing Water tof-flow from l the lirontV end; of the cylinder l through these rportspastlthe leather cheek valve 72 `and on through'the pipe-hlfte the heating' receptacle to` keepup the desiredV How through 4Qth'e; outletpipaf This n io'vementv ofV the piston lmember withdraws the/ end 'of the ste1n'69 lfrom engagement with. the' main gas valve 76 and leaves the latter free to be actul 4 v w4 the stirrup '88 out `'of engagement .with Vthe position.vv by `the spring 95', thus leayihg the' 3oV port 92" open'. 'lhis 'will fallowl gas to pass l throughthegports VP(Sland 92gto the. right' *ated-in, 'itsfmovements solely. by thev thermo# statically Controlled means.4 'If the temperature of; the water in the-thermostateha-mber is less thantha't '.desiedthe thermostat? levers 85 and 8'( will be' depressedto. such' a position as `to-keep A'tl 1e`-l v`ver cross-bar of.

headof thestem 90, and under these circum staneesthe yalye9`1vyvillbeheld in its lower hand side/ef the diaphragm Wand the pressure l, ofsaidf gas' on `this- 'side of the dia.

35.` `to openfl-asfsoonf the' stem 69 has been` site iside. Fuel thereupon HOW through *thei'gas valve ea'singjfioin the 'gaslinlet pipe Het meg-assumer papeterie-passen to the igilitedby tlie usual` pilot light providedfor mairibiirrierS of theheater'whereit yWillbe l thermostat `'("sham-ber" rises' thev piston member toi . 83.,"ofsaid theriiiostatwill expandallowing the, thermostat levers 85 'and 87 and the Astir#v .rup 88 temeva-'upwardly undertheJ tension of the vsp'ringj BQ-'imtil *the lower Scro'ss-bar of saidfstirrupg engagesV 'the 4head ofithe valve manfgasvel l fail in: temperatur theelosedipo'siti epee - will once more be opened'adrriitting a fresh 1- .supplyfof gas to the heating bu'rners,l ;These" opemng'and closing movements. of the-main gas valve will continuefaslthe tempe rature4 of the flowing Water falls'below .lori rises 'may beset toaet on the eontrol'yalve 91, thi s point being Varied at `Will lay-adjusting the .screw stopped the pressures on the twosides ofthe ber Will be returned 4toits elosedn'position as shown in` Fig.- Z-jinf which, as before stated, thefend' of 'thestem 'GQfiSbrought 8e,l

into engagement Withthe maingas valve .76 and holds the latter tightly closed toits seat regardlessof the position 'of the thermo.`

static control parts', If; for any reason,the" Water actuated' member ,62 should: stickini its opened'position any injuryto theheater cannot result, since the'main gas Valvefgyvill 'under suoli eircjumstancesx l remainunjder the' above they point lfor 'which the y thermostat f Water actuated piston memberHZ' Willgat once be equalizedyand'the saidpiston'mem-,l

86." But Vwheni'the .iowb `Water is eontrol of the: thermostat mechanism iandvf the latter- Willoperate lkea straight thermestati-c Qontrol to shut offthe fuel supply' `"to thefheating burners, Whenever' the temperature of the water inthe heater coils rises tinued maintenance I of the thermoetat member at thete'mperatureof the W ter inthe -v heater e'oils, a circulation valve97is-vprof vided,whiehis opened by gravity Whenever abotfe Certain pointy- To insure-the con Vthe dow of Water ceases and 'allows the-* l Water toeirculate freely 'between the ilet;

4and outletopenings'j and 81 and? the 'ther-f K'Inostat tube and"cross#Connectiony 9 "When' the Water is flowing this circulatiol valve 97: Vlsraised by the pressureof the lowmgfwater wthus. -cuttingthe' porti yopening tol the j cross-connection 981 and 1 forcing all of the Water to pass throilglith'e -heating coils' But unless the. Water-*aotuatedl 'member'Q isg verytightly wedged ill its -open' position; 1i. y

matically4 eloge'slthef-perforated `end ofvithe 'i nyfurthe'r heat-' oli,y the left hand "rees-itrbaek to. already statedfv l penby theWedg-` atter 1n the 'portop'ening hed-ef likely" w:

vs'everef'eonditions ciselyv the same in `all respects as that shown inv Fig. v7 save that the ivateractuated mem- `ber 100 does not act dlrectly upon` the gas valve 76 to hold it"closed. when no Water `yis {iovving but acts upon 'an auxiliary valve 101 which opens andT closes the port 78 through `Whlchfgas passes from the gas inlet pipe H to the chamber 79.

-The .operation of this mechanism is the l described save that 'Whennojivateris flowing2 the closing of the valve- 101 by the sprlng 102 prevents anygas entering the chamber 79 and acting upon the bach .e. the right hand side, of the diaphragm 77. This Willprevent the lgas valve 76 from A4being opened when no VWater is flowing no matter what may be the position of the valve 91. When the iovv of Water is started the Water actuated member 100 is moved to the left opening the valve 101-4 and admitting to the lchamber 79. The admittance and discharge of gas to and from the back of the main gas valve-diaphragm 77 is then t5 l:ontrolled bythe movement of the valve 91 imder'theaction of the thermo/staticl control mechanism '1nl exactly the same l'Way as 1n the apparatus shown in Fig'. as long as Water' continues to HoW the opening and v :losingfof themain gas valve. 76-vvill be' controlledtentirely by-.the thermostati'cally ,40 cesof gas to the back of the main gas valvel Vdi pliragm 77. 'After the very next-move- In nt of the thermostat which discharges the gas .in that chamber the actuating pressure means Whichoperates the main gas valve is elilininated and said gas valve will therefore remain permanently closed under the lp essure of the gas -on the main gasvalve s de of the diaphragm until the port 78 has nce more been opened by restablishing a iiow of Water through the heater coilsand a {new supply of gas admitted tothe cham- *ber 79.

1 l In Fig. 9 I show another embodimentof my improved control mechansim. as delsigned *forl use on the .so-'called instantaneous type of water heater. In this construction I place the chamber 634 which con- .,tains the Water actuated member-624, above the thermostat chamber 804; and lead the ,60 stem 694 of said Water actuated member down through a stuffing boX 103and'a-long .the side of the thermostat chamber 80f jthrough another stuing'boX on the top lof the main vvalve casinglVI vgzhich,iscse--4l WerJ nd,

cuseltjto and forms a part of tlji same' in'all respeotsas that 'of the one just Vber but arranged at large angle th :the purpose of this arrangement! offthe'thermostat chamber 80".

chamberGB? through a pipe' 644. The pistonl member is somewhat similar inconstruction to that shown in Fig. 7 being pro-- vided with a downwardly projecting inthe top coil of the heater," The central part ofthe piston member 624 is provided5 with small ports 105 Whic'h'lead from the opening communicating with the inlet 664 to the upper end of the cylinder G34, and a fiat puppet valve 106l is hung on a stem 107 loosely mounted inthe top cap of the'cylinder, in such manner as to closethese ports i "Cold 1s led into the lower end vof the piston boss 10,4:l on. the lower" 105 as soonas the piston member begins its the top capl of the-' cylinder, and a second spring concentric'vvith this first spring'is interposed bet-Ween the, top of the piston '624 and thisv same cap y.for the purpose of holding said piston-normally 1n the position shown in the figure. The water after entering the inlet .6634 and passing .through the coils of theheating receptacle, emerges from .the hot water outlet 81, enters the lower.

end of the thermostat'chamber 804, passes up through the latter, and finally enters the pipe 82*` Whichjcommunicates with the house supplyv system. Atthe up )er endv of `the upward movement. This valve 106 is 'held down by a spring interposed between it and cylinderGB1A there is a-port 08 Which'opens into the pipe 82%*vvhen the piston member is in it'svloivest position and theports 105 are ope'nand allows the water to circulate throughthe thermostat chamber between the inletg? and the outlet 814 Aof the heaterA coils. -Located in the thermostat chamber l 804 is 'thejcontrolling thermostat me1nber, which is ofthe vsame general construction as that shovvn in Fig` 7, save that'i'n F,this case the .inner negative element 844 is provided "Withpivot points or knife edges at both ends, and is preferably of larger ameter at the center than `at the ends so as. to resist momo-effectively the compression strain exerted on vthis part When'the outer positive element v834.0f the thermostat `con,

tracts. The lower knife edge 'or pivot point Aof the inner thermostat element 844 engages With' the shortarm of a thermostat lever 109,. This thermostat lever differs from any previously ld escribed n-that the axis of the short arm isv not normallydisposed tothe line offengagementof the thermostat "mem:y erete. ng... to

1mg@multiplication: @fiaments of; .thermostatL element lwithout the Vnecessity .lofi using `fa y,long thermostat lever yithoutl -the necessity n of using al comv Y; hermostat leverjgsystem. suchas is `I5- commpnlyfemployed; dr such" for example,

' aslislshownrlsin Fig;

vement of the valve w `'the screw..V 110 engages.4

wlli'chlads "'t `the ejector discharge orifice andfopen "thefport' 93? by a compression Siprflgl'ljll, "The: --Inain gas valve 64 -is Y untdiha horizontal position. atthe cen. tbrf of fa'thinlfleXible" leather diaphragm 7 7 4,

hen` no water f` is flowing through the this valvefisf held down against its he- 'engagement of the lower end of L"1,694" iivithithe'upper side of the qIn "construction I also usual cut-:o plug valve, which `gas,"directly in the chamber with gasv supply pipe- H communicates; L Iprovidefa :cored passageway '112 lead-l '5' oiin jthefoutside' of'thismain cut-off a 'tul fe 'l.113` ',which leads to the pilot e, eta., ,n

Chani'smis slightly dierent from thefmechanism of Fig'. 7 and is as t il figura'andf allpoininunication 11s cut off be'- j '50 ttwen; pipel-y G4-' and the cold water inlet '@664, saye forfsuch 1small flow as is usually fprolvided for toltake4 care of the discharge.

zi'froinleakyffaucetslji As soon] asi "an-y large t and -lhfu SUPQI'lQIY .,PSSure of 'the water Zon l 4theblower side,y of-thepiston fmember then (5U-:raises the latter-,therebyclosingrthe "ports-f 4main lports leading "the cylinder to the fr entirely' shutting olf the' il'A charaoter 'of -the operation of f 'no water is flowing through fltheii'heaterfthe piston member 624 1s 1n its 'sten finemberlgwithdraws f the-'endof tl"I vthe man gasvalve, and `leaves the latteiifi'ee- "to be-movedby the thermo'statically?,regu# lated `gas pressures on the main' valve dia-v phragm .774. I If the temperature ofthe liowingfyvater lis yless thany thatfor which the thermostati control mechanism isset to act, the thermostat lever 109 is lifted'to such position that the 'screw 1 10 isout'of engagen t ment with the stem 904,y and the valve, 914

visQtherefore'raised by the spring 111 so as to leave the port 934 open and relieve the up- 'per side of. the main gas valve diaphragm 774 from any pressure save that of the,at 'mosphere The lower side of the diaphragm 774 is however constantly exposed. to the pressure of the' gas entering the gas valve' chamber from the supply pipe H, and this pressureraises the main gas valve 7 64 from its seat as soon, as thefrestraining pressure of the stem 694 on the back of this valve has `been removed?. This allows thel supply of fuel: to' pass f romthe supply. pipe` H' through the pmain cut-od valve" and through l the chamber ofthe gas valve 'casing M and `liow out through the gas outlet pipe I to the main burners. of the heater'where vit is ignited yby the flame o f the pilot light su'pplied through `the pipe 113. As the temperature lof the flowing water' rises the thermostat 'member expands lifting the negative thermostat 'member 8454 and allowing the thermostat let ver 109 to bedepressed by its spring 114;4 unlitil the screw 110 has made engagement withv f the end ofthe stem 904 and moved thev'valve 914 down until the lower port 934has been closed, the port `924 being simultaneously' opened. `Gras will now flow through the passage way 784' and port 924 on into the" shallow chamber back, e., onthey upper side, of the main gas valve diaphragm 77 4, and the gas `pressures on the two sides vof )this diaphragm 'now being balanced; the.y

main gas valve 764 will be closed by gravity thus shutting oli' thefliow of fuel to the gas outlet pipe l and to the main heating burn- 'ers supplied thereby.

the flowing water willthus immediately be- `gin to fall and this will. cause the thermostat to contract thereby lifting the thermostat lever 109 and-withdrawing the screw .110 from. engagement with the valve' stern 904. This in turnwill -allow the valve '91'L tobe lifted by its ownY sprinnllfto the first .described position in which, Qenn1924 is closed and the opening of this atter port allows the gasv fback '.of the 'diaphragm 774-jto flow out through the passage way 9114'. and the ejector v .orifice at the end thereof into the now emptyy gas outlet pipe L As soon asv the pressure `of`=t ,he gas on the top of the diaphragm has "thus been relieved-the unbalanced pressure old-afwater .inlet I Gfflihis'liftingfof; the

' A more lift the mainggasxvalve 764 from .its

ort 934 ish opefrcd; The

of the gason the lower side thereof will once and admit a fresh supply of fuel to the The temperature of t burners. As long as Waterl continues to flow through the heater, the ste`m694 is kept lifted out of engagement with the back of the main gas valve, and the latter will continue its opening and closingl movements .under the control ofthe above described thermo- .static mechanism, the point of cut-oit being varied at will by the adjustment of the screw 110.. But'as soon as the flowof Water is stopped thel water actuated member 624 Will be returned to its lowestV position both by the action of gravity, and ,by` the action of the springs in the cylinder 684, and the stem 694 will once more be brought into engagement with the top of the m'ain gas Valve 764 holding this valve closed, no matter What may be the position of the thermo-staticallycontrolled valve 914,.. lVhen the piston 624 is in its lowest position thek ports 105y are opened, as alreadyexplained, thus affording an open passage for the circulationof .Water through the thermostat chamber between the inlet and outlet openings to the topand bottom of the .heater coils.

v Instead of discharging the gas above the.V

main gasl lvalve diaphragm through the ejectororifice at the .end of the passage-Way 9-14 into the main gas outlet pipe I, I may of course discharge it into the pilotfn'light tube-113 through an ejector port-indicated l bydotted lines only-similar to that lillus-- trated in Fig.

In Figs. 10 and 1 1 I have illustrated, somewhat diagrammatically, another construction .of thermostat .member'jand therf `mostatJ lever which`may be used-withsuch slight modifications as are readily apparent to any one skilled in the art-in conjunction with any of thepreviously described mechanisms. The particularadvantage of the thermostat mechamsinvshown v1n these v l figures.. is that it 'occupies very small amount of space, and i's lalso 'of very` sim- L Y l 4'-iple and inexpensive construction.l It con- 'cross-section (see Fig. 11)` sup orted at, its

sists ofi-5a. central bar1115 ot' trapezoidal 'center in any suitable manner on the yWall vrofthe thermostat chamber -or box, and teryIni-nating at each venclin a knife edge which `forms al bearing lfor a segment ofy a small grooved coiled-pulley. This bar is madeof nickel steel,'invar metal, ork some other material having a verylow or practically zero coefficient oi thermal expansion. In f `the upper oneofthese pulleys 11G they radlrof the successive pulley steps are 1n the ratio of the even number, 2, 4,26, 8, etc.; v1n the lower pulley 117 these radii are in the ratioy Y tof theoddnumbers`1, 3,115, 7, 9, etc. One

end 118 of a'wire, whichvis preferably made of hard drawn copper,.silver, brass, German silver or phosphor bronze, Vis securedfto'the upper 'end of the bar 115, and' 1s passed l around the successive steps of the lower and i vupper voned` pulleys 117 and 'as shown in the figure, and is secured at its outer 'lreeend 119 to theshort arm ot'a thermostat lever 120. It will be readily lseen that when this wire expands or contracts with reference tolthe central bar 115 the'movement of that part of the wire which engages with the successive steps ofthe pulley eleential movement of thoseV steps themselves sov that, with a vuniform angular movement of all of these pulley' elementsas a whole -ments is exactly'the'sameas the circumferthere is no slipping of successive parts of out using a multiplicity of levers and withv out using al lever having an undue overall length. vIt. 1s further readily -seen that tlns yexpansion and contraction movement. ofv the point 119 is the lsame as that4 which would be obtained for thesame change in tcmper-. ature with a vstraight wire whose tota-l length was' equal tothe sum ofthe lengths of all the strands orl sections of 'wire running between the two opposing coned pullejvv members. If the length' ot' each o-these strands,` c". e., the length of the bai-*115 between its terminal knife'redgemis made only three inches, and the total number of strands is fifteen-as shown in the `figure-- the total expansion` .andcontractin etl'cct' is the same as wouldVA be 'secured witlLja straight wire forty-five inches long.' The difference between the coeiiicients ofexp'ansion of hard drawn wires .such v as I- have alreadyjreerred t0 and Anickel steel bars is about ,00001. Hence theplinearv movement of the end of the long" arm of the thermo- Statl lever and' of ythe .part 121 moved thereby would* be about 'onc-'eightieth of an inch for every' change ot' temperatureof '1 K. degree C. if the partsave1e-ot' the dimenysions above assumed,v and the .length ot thelong and short arms-v ot'i'the lever '120 "were fit 'mean a movement of the part 121l ot' over' one-eighth of an inch forevery 10 degrees change in temperature-a movement that is ample and even excessive for the operatior of such parts as are to he moved in mechanisms'otl vthe class under consideration. The actual dimensions ofthe 'parts will of course `vary according to .the forcen'liich itis desired' to exert upon th@l partlil. In water heater constructions such as this application describes the force required to move the thermosta'tically 'controlled' parts is very 1o inches wide dee The side oi?l the vbox maybeleft open an the mechanismiinx'nersed directly in the smal-1,'` and a No. `QOto No. 24 gage wire'is amply large ,to -eXert'the required force, on'

the thermostat lever without permanent stretching or distortion. For wire of this 5 .smalhdiameter 'the coned pulley elements may :b'e correspondingly small, yand 'the whole' thermostatie mechanism-fleven and fallf-inclosed in a. shallow'rectangular boX aboutl 'tive 4inches long, one 'andl one-half and one-quarter 'et an inch stream Vof hot water or the box may be closed-or 'if 'desired may be partially lled with ,oilethe stem El being',` led out through' a suitable stuling box.

v"It will'now be readily apparent to those reading the preceding description of various mechanisms which embody my improvevarious. modications may \be made in said mechanisms without departing 2e ments.. that from my invention, and that thelsaid mechanisms and modifications thereof may be ape plied to various types'andfclasses of water heaters with only sueh detail changes as Vby thoseslrilled in the art.

Havingthus described my inventiort and will'be readilyunderstood and appreciated illustrated its use, what I claim as new and 3o desire to secure by Letters Patent, 1s the fol-- lowing; Q l. In combination` inawater heaterl system, a burner, to theburner, operated by' thepressure of 'the'gas in the #conduit forl openingand closingzthe saidl valve, 'thermostatio means operated by' the water in the System for- :ontrolli'ng said-last 'mentioned means, and. means controlled by .4 40 the water pressure whereby the said 'valve is held closed untilrt'he'outlet from the heater is opened.

-. 2. 'In combination in awater heater sys-v tenna burner, a conduit for .supplying gas to the burner, a valve inl the cpndu1t,' a ther`-v mostat operated by the water ofthe system,

actuating means operated by the pressure of the' gas in the conduit for opening an closing the said valve, means interposedrbetween the-actuating means and the thermostat and controlled by thethermostat for governingthe application of vthe pressure of gas in the conduit to y tem', aburner, a vconduit for supplying gas toz'the burner, a valve in theconduit, a thermostat operated by the water of the system,`

' a movable member operated by they pressure 'of thegasin theconduitffor opening and elosing the said v ,alve, pilot valve/means oon- 'trolled by theA thermostat wherebythe gas Atem, aburner, to the burner, a valve inthe con held closed until the outlet romztheheater a conduit for supplying gas' a valve in the conduit, vmeans' the said' actuating means, andl means controlled by the water` the said Avalve is held.'V

upon the vsaid member 'iis controlled,ai1d`y`l means controlled by the water pressre 'whereby the saidvalve, is held eloseduntil the outlet romthe heater is opened. y,

4; In combination ina water'heater'tsys-'je, 4a conduitffor supply ng` gas* t dilitia" the# mostat operated by thewater' of 'the system, A a movable member operatedby thepressure A of the gas yin -the conduit .for opening and closing the said valve,lpilot valve means een- .troll'ed by the thermostat vwhereby the pres sure ofthe gas'on: one side of the member is controlled, andv means' controlled lthe water 'pressurefwherebyg the-1 said lvalve is 30 is opened.

5. In combination-in a 4water heater sys tem, a burner, a conduit Jfor supplying gas' to the burner, a .valve in the conduit, a ther- 35' mostat operated by the waterof the system,

.a movable member operated bykthje` pressure ofthe gas'in the Vconduit- :tor opening and closing the ,said "valve, pilot valve ,means controlled by Vthe thermostat vwhereby the gasfp-re'ssure is admitted to`an`d `exhau'sted `lrom o ne side of the' said member-to secure thel movement'thereoLthe 'gas pressure on the'ot-her side of the member being substan Atially uniform, and means controlled bythe water 'pressure whereby the said valve is held closed until ythe outlet from the heater is opened, v y

6. Incombination'in' a water heatersystem, a burner,

mostat operated bythe water of the system, a movable member operated by the pressure ofl the gas in the conduit for open-'mg and' closing the said valve, pilot valve means eon 'its' trolledby the thermostat whereby the gas pressure is admitted to one side of the said -member to cause ythe .closing of the valve when the' temperature of the water rises v'above a. .give n point,`and whereby the gas im :pressure is cut oil. `from such side of the memberl and the gas then exhausted from suchside of the member when the temperature 4of the water drops belowy a given point, andA means controlled by Athe water pressure Whereby the said valve isheld closed until the outlet from the heater is opened. 71111' combination ina water heater system, a burner, a conduit yfor vsupplying gas `to the burner, a main vvalve inthe conduit, a thermostat operated by the water in the sys tem, a movable lmember operated by the pressure of the gas in the conduit for open ing and closing said valve, a pilot valve for admitting gas pressure behind the said meniber to cause its actuation and the actuation of the said main valve, an exhaust passage leading from behind the main valve to the outlet side of such valve, anfexhaust. valve for controlling 'the dow of gasthro'ugh said 13g a' conduitfor supplying gas we tothe burner, a valve in the conduit, a there passage; and 'a check valve for preventing a signed my name in the presence of 'the two back ow through said passage, the. pilot subscribed' Witnesses. 4

and exhaust Valves both bein@ actuated from v f the thermostat, and the plvt valve being FRANK L' O n ADSVORTH' 5 opened When'the eX11al1stw'a1\'e s Closed and Witnesses:

vice Versa. LETITIA A. MYERS,`

In testlmony whereof I have hereunto f ARGHWORTH MARTIN. 

